AFAIK, the only difference between a standard Hornet and a K-Hornet is in the blown out shoulder area, so if your case is expanded near the head/rim, as if it fired while lying in the bottom of an oversized chamber, it most likely was...............

I would think something's up with the chamber proper, to make it larger than a standard Hornet chamber, allowing the expansion, or the cases were excessively sized down prior to the fireforming (which could amount to the same thing, relatively).